3%NaCl水溶液中におけるフェライト系ステンレス鋼溶接継手の腐食疲労挙動

概要

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Axial fatigue tests have been performed using welded specimens of a ferritic stainless steel, SUS 444, in 3%NaCl aqueous solution, and the effect of corrosive environment on fatigue behaviour was studied. The fatigue strength of the welded specimens in 3%NaCl aqueous solution decreased considerably compared with that in laboratory air. Fracture occurred at the toe of weld due to stress concentration, but fracture surface near crack initiation site was brittle, indicating enhanced small crack growth by 3%NaCl aqueous solution, thus in turn leading to decreased fatigue strength. In order to further understand the corrosion fatigue behaviour of welded joints, additional fatigue tests have been conducted using welded specimens whose reinforcement of weld was removed. The fatigue strength of the welded specimens without reinforcement of weld in 3%NaCl aqueous solution decreased significantly compared with in laboratory air. Fatigue cracks initiated from corrosion pits generated in HAZ near the boundary between the weld metal and HAZ at much earlier stage of fatigue cycling and then grew faster than in laboratory air. It was concluded, therefore, that the decreased fatigue strength in 3% NaCl aqueous solution was attributed to corrosive enviromment-assisted crack initiation and growth.
社団法人日本機械学会の論文
2006-01-25